EP 0 968 371 81 discloses and describes a fluid cooling device comprising a motor that powers a fan impeller and a fluid pump. The fluid pump takes fluid from an oil reservoir and conveys it into a hydraulic operating cycle. In the hydraulic operating cycle, the fluid (hydraulic medium) is heated and routed to a heat exchanger. From the heat exchanger, the cooled fluid is recirculated to the oil reservoir. The oil reservoir of the fluid cooling system is configured in the shape of a basin with particularly high-reaching basin edges that are suitable to form a housing part for receiving the fan impeller and an air-routing chute for a heat exchanger of the fluid cooling device. With the fluid cooling device, an oil reservoir can be provided in an especially compact assembly for storing and circulating large fluid volumes.
A control system and a method for controlling the speed of a plurality of fans for cooling a plurality of flow media of a machine unit are disclosed in DE 100 62 534 A1. The speed of each of the plurality of fans is controlled specifically according to an individual heat dissipation requirement of heat transfer cores. For one temperature sensor, respectively, of each of the plurality of flow media, current temperatures are monitored. Each sensor can be operated to generate a signal that displays the temperature of the respective flow medium, while transferring the signal to an electronic control device to control the respectively singular speed of each of the fans.
Using the previously described solution, temperature-control, especially cooling, tasks for a fluid of a hydraulic circuit can be basically implemented. However, particularly the temperature of the fluid that has passed through the fan device is, seen in absolute terms, dependent on the respective and varying ambient temperature of the hydraulic power pack. The output temperature of the fluid therefore fluctuates in the known hydraulic power packs and fluid cooling devices after it passes through the fan device.